Within the framework of imaging methods such as magnetic resonance tomography (MR), computed tomography (CT), positron-emission tomography (PET) or single-proton-emission computed tomography (SPECT), persons are usually introduced into a tubular measuring chamber. Understood here are such measuring chambers which do not take the form of closed tubes, but instead encompass a C-shaped measuring chamber, i.e. tubes which are open on one side of a patient.
Special patients, like for instance unconscious, seriously injured or sedated patients, small children or patients with phobias must be accompanied during an imaging scan in a particularly vigilant fashion by the operating personnel. It may therefore be necessary to permanently visually monitor the location and/or the physical health of the patient in order for instance to identify a deterioration in the health as well as the appearance of problems such as disorientation and anxiety and to promptly counteract these.
If such visual monitoring is not possible directly from the site of the system controller of the imaging system, for instance if an operator of the imaging system has no direct visual contact, for instance through a window, with the patient, a video monitoring system may be helpful. Such video monitoring may then also be necessary if the movements of a patient are to be monitored automatically, so that it is not imperative that an operator permanently intensively supervises the patient during the imaging procedure, but instead is able to concentrate more on the parameter settings of the respective device for instance.
Video monitoring systems for imaging systems are currently already known. They are usually realized with the aid of a video camera, which has been retrospectively and/or additionally fastened to a wall of the chamber, in which the tomography device is positioned, during the system installation of the tomography arrangement. Alternatively, a video camera can also be attached to a casing, for instance the magnet casing of a magnetic resonance tomograph.
DE 102 10 050 A1 discloses a camera system as the basis for a relative positioning of a patient. An image matching with previous image recordings from the same perspective can take place by image recording with two independent recording axes from at least video cameras. This image matching is used as a basis for an accurate repeated positioning of a patient on one and the same site in a tomography arrangement. The video cameras can operate here in the visible and/or infrared light wave range. Patient monitoring is not provided here.
DE 101 09 219 A1 discloses a further camera-based system with a similar design with the same purpose in terms of accurate positioning.
A few disadvantages result with the known video camera systems however. For instance, the camera viewing range cannot be adapted as a function of the patient positioning. This is the case for instance when introducing the patient head first into an examination room. The facial region here is only poorly visible and/or in the case of particularly large patients the middle body region covers other body regions of the patient. The field of view of the patient can also not be monitored if in the case of MR examinations closed head coils cover the head and/or the face of the patient in the viewing direction of the camera. Different customer wishes in respect of the display of the patient's field of view and/or a certain patient region in the measuring centre in the case of any patient position could thus previously not be completely covered in such camera solutions. One further problem consists in the additional assembly effort of the camera onto the wall. Furthermore, when assembling the camera onto the magnet casing, the region in front of the measuring chamber is itself restricted by the camera and is thus only accessible for an operator with limitations if a patient is also to be treated during the imaging procedure at the same time.
A monitoring in the case of examinations with lower levels of ambient brightness was however previously impossible. To this end, particular note should be taken of the surrounding patient illumination being intentionally switched off during the examination of sedated patients for instance, in order to aid the calming of the patient by means of a darker environment. This precautionary measure nevertheless conflicts with the particularly high safety requirements in the case of sedated patients, which have to be observed as accurately as possible in order to be able to respond promptly in the event of dangerous situations.